Grade Six Music Theory - Harmony Lesson 9: Realising a Figured Bass
Introduction to Realization
So Many Rules! Before we begin to make our own realizations, there are a few things we need to learn about first. There are quite a lot of rules when it comes to figured bass, but don’t panic! First you need to read about the rules and guidelines, then you need to do lots of practice exercises, and be prepared to make lots of mistakes!
With each practice exercise you do, you will get better at remembering all the rules. It also helps to understand why the rules exist. You must get into the habit of triple-checking your work too, because in figured bass, mistakes hide everywhere!
To get started with figured bass, you need to know the rules about:
Click the links to read about each rule in detail. Here is a summary:
No consecutive 5ths or octaves, and also check for “hidden” consecutives.
The soprano line should have a nice melody. The alto and tenor lines just fill out the harmony. No wide leaps, augmented or diminished intervals. Use as little movement as possible most of the time.
Always check you have doubled the right note – usually the root or fifth.
Don’t let parts overlap, and make sure they stay in the right range of notes.
How to Do It
These are the steps you need to follow. More details are given below.
Work out the key of the piece.
Write down the chords you need by name.
Write the whole soprano line.
Fill in the alto and tenor parts, chord by chord.
Check for errors and rewrite where necessary.
Repeat step 5.
We must stress how important it is to CHECK CHECK CHECK everything you write in figured bass!
Step 1 – KEY Look at the key signature and decide which pair of keys it could be in – the major and its relative minor. Look at the figures – if you see any added sharps or naturals, it will probably be the minor key. Sing through the bass line in your head to confirm whether it’s major or minor.
The key signature is two flats – is it Bb major or G minor?
The sharps and naturals in the figured bass tell us that it’s most likely to be G minor. Try to sing the bass line slowly in your head. You can press the play button to listen to it.
Step 2 – CHORDS Look at the first note in the bass line and the figure underneath it.
It’s a Bb, and it has a “6”. Remember that “6” really means “6-3” – we need to add the notes which are a third and a sixth higher than the bass note.
Starting on the bass note, count the lines and spaces until you get to 3: Bb – C – D. So, D is the third note up. Starting on the bass note again, count the lines and spaces until you get to 6: Bb – C – D – Eb –F – G. So, G is the sixth note up. Put the notes together: Bb – D – G and work out the name of the triad. This is the triad of G minor. Underneath the stave, make a note of three things:
the chord name (G minor)
the chord notes (G – Bb – D) and
the chord number & position in Roman numerals (ib)
(As you get better at doing figured bass you’ll find that you don’t need to write out all this information. But in the beginning it’s a really good idea to do it this way, because it helps you to understand & learn the rules of harmony, and it helps avoid mistakes. You will begin to see that there are common patterns of chords, for example, and you are less likely to write in the wrong chord notes accidentally.)
Write in ALL the chord information in this way. Check your answers in the table:
G Bb D
D F# A
G Bb D
G Bb D
D F# A
G Bb D
C Eb G
G Bb D
G Bb D
D F# A
G B D
Step 3 – SOPRANO
Starting at the beginning, choose a note to start your soprano line on. How?
A good soprano line
has an interesting melody without too much repetition of notes
moves in contrary motion to the bass line
The soprano line can take any of the chord notes in your list, and you can safely double any of the bass notes EXCEPT in chord Vb – (we haven’t got any Vb chords in this exercise, so that’s not a problem!)
So, for our first chord, shall we choose a G, Bb or D?
Look back at the chord notes you listed in step 2 – in the first six chords you will need a D – so the note D will probably be better in the alto or tenor parts, because those parts should move very little, whereas the soprano part needs to move mostly by step so that your listeners don’t die of boredom! Don’t choose a note which will get you stuck in a rut! So let’s go for a G. High or low? Well if we want our soprano part to move in contrary motion to the bass, we’d better not start too high, or we will quickly run out of singable notes. So we’ll choose the lower G (the bass is low at the start, so we have plenty of room to fill in the alto and tenor parts).
(Often, the note you choose first will not be the best one and you’ll have to go back and change it later, but we need to start somewhere and this is the best place to try!)
We write the soprano note in as a crotchet, because we can see that the chords change on each crotchet beat. We write the stems upwards, because we will write the alto line on the same stave, underneath the soprano line, with stems downwards.
To choose the next note, we need to remember some guidelines and rules:
No consecutive 5ths or octaves (including hidden consecutives)
No huge leaps or illegal intervals
Move in small steps where possible
Contrary motion is best (but not compulsory)
The notes we can choose from are D, F# and A. We want to use contrary motion, so the melody line needs to move upwards or stay the same, because the bass moves downwards.
So, shall we choose D, F# or A? D is ok, but perhaps we should avoid it for the same reasons as before (save it for the tenor or alto, which need repeated notes). F# is nice and is a semitone step but is similar motion and getting quite low on the stave. A is in contrary motion with the bass. All of the choices are allowed, but A seems to be a good choice, so we’ll put A.
Next, we need to choose from G, Bb and D. What do you think is the best choice, and why?
D isn’t great, because it makes a big leap
G is ok but a little boring
Bb is good because it uses contrary motion and is also a semitone step from the A. Always use a semitone step if there is one!
Continue in the same way, until you’ve finished the soprano line. Remember there is always more than one possible answer when realizing a figured bass. Read through our decisions for each note to see what influenced our choices, but don’t worry if you think you would write something different. Just make sure you haven’t broken any rules! Each note is numbered so you can see why we chose it, and the reason why the other notes were not chosen is in brackets.
G- contrary motion. (Bb is ok, high D is a hidden consecutive octave).
F#- in a 6-4 /5-3 progression the 4 must resolve to 3, no choice here.
G- semitone step (Bb is an illegal interval, D is hidden consecutive 5th)
C- contrary motion (Eb is a hidden consecutive 8ve, G is ok but a “rut” note)
D- stepwise contrary motion (Bb similar motion, G is a “rut” note)
Bb- contrary motion (D is a “rut” note, G is a large leap)
A- 6-4 / 5-3 progression the 6 must resolve to 5, no choice here.
B natural- stepwise movement (G ok but we’ll need an F# which resolves to G too, D is a big leap)
Now we have a soprano line that doesn’t break any rules, we can attempt to fill in the alto and bass parts. It’s important to remember to be flexible – usually we find that we have to change something in the soprano line to avoid breaking rules in the alto and tenor parts.
In the above list of reasons for not choosing a note, you should realize that:
It’s ok SOMETIMES to
use similar motion
have a big leap
It’s NEVER ok to
have hidden consecutives
use illegal intervals
go outside of the normal voice range
Step 4 – ALTO & TENOR Now we need to fill in the inner parts. The number one rule to remember here is that there should be as little movement as possible – if you can keep the same note in the same part then do! Complete each chord one by one, and then check it carefully to make sure that you haven’t written any consecutive 5ths or octaves, and that you’ve doubled an allowed note. Re-read the rules of doubling now, if you need to.
Let’s start this one together too. For each chord, refer to your chart from step 2, and work out which other notes we must (or can) add into the chord.
You should make sure the tenor, alto and soprano parts are not too far apart from each other – an interval over an octave is too big. Between the tenor and bass parts big intervals are absolutely fine.
Chord 1: We need a D and can double any other note. It’s always safe to double the root, so we’ll add D in the alto and G in the tenor.
Chord 2: We need D and F#. The alto part can repeat the D, which means the tenor takes the F#. That works well because the tenor part also moves by a semitone step.
Chord 3: D and G. Alto repeats D, tenor moves by step.
Chord 4: D and Bb. Alto repeats D, tenor jumps up to Bb.
Chord 5: D and A. Remember this is a cadential 6-4. The tenor part must fall to A, so the alto can stay on D yet again!
Chord 6: D and Bb. Alto D, tenor Bb (another nice semitone step).
Chord 7: G and C. Both parts need to move. We put the G in the alto so that the top parts have narrower spacing, and the tenor/bass parts have the widest spacing.
Chord 8: G and D. Alto repeats G, tenor D (stepwise movement).
Chord 9: G and D. Both parts repeat the note.
Chord 10: F# and D. Alto semitone step to F#, tenor repeats the D.
Chord 11: G and D. Alto semitone step to G, tenor repeats the D.
Step 5 – CHECK! Step 5 is possibly the most important step of them all! It really is easy to make mistakes in figured bass because you need to concentrate on so many things at once.
These are the checks you need to do every time. When you come across a mistake and then fix it, you need to start your checks right at the beginning again, because fixing one problem often causes problems somewhere else! (Sorry!)
While you’re practising, include playing through as part of your checks. Play it on a keyboard and play it slowly. This helps your brain to associate the chord sounds with the symbols your eyes can see.
If, horror of horrors, you find that every time you fix one mistake another one appears, you probably have a faulty soprano line. If it’s really bad, it’s usually better to rub it all out, go and have a coffee and then start again!
Chord Notes. Check that every chord contains the right chord notes and that the note you have doubled is allowed. Read each chord slowly and place a tick under it after it’s checked.
Consecutives. Check each possible pairing of parts for consecutive octaves and fifths. Write out the following: S-A, S-T, S-B, A-T, A-B, T-B. Then follow each pair of parts, one at a time, watching the intervals carefully. If the parts move in oblique or contrary motion, you’re safe. If they move in similar motion check for consecutives. Tick off each pair of parts as it’s completed.
Hidden Consecutives. Recheck the bass and soprano lines together. If the two parts make a 5th or an octave, make sure that it is approached by contrary motion, OR that the soprano part moves by step. If neither of those two things are true, you need to re-write. Look along the soprano and bass lines. If you find a 5th or an octave, check the conditions apply.
Voice Leading. Leading notes should resolve to the tonic, no illegal intervals, mostly stepwise movements. Read each part separately. If you see large intervals or anything suspect, double check that it’s allowed.
Cadences. Cadential 6-4s must move in the proper way, 6 moves to 5, and 4 moves to 3. Look at the figures. If you see 6-4 followed by 5-3, it’s a cadential 6-4. (If there is a 6-3 without the 5-3 after it, it’s a passing 6-4 and more flexible).
Overlap. Make sure none of the parts overlap. Check particularly between the alto and tenor parts as this is where errors creep in.